1. Field of the Invention
The present invention relates to a color measuring apparatus, a printing apparatus and a backing plate, and more particularly, relates to a color measuring apparatus that measures color using a backing plate.
2. Description of the Related Art
An inkjet printing apparatus is sometimes equipped with color measuring functionality for color correction. When measuring color with a printing apparatus having color measuring functionality, color patterns are printed onto a sheet, and color information for the color patterns is measured using a color measuring device. The color of print data on a monitor is compared on the basis of the colorimetric data, and the comparison results are applied to the next printing, thus making it possible to obtain desired color reproduction.
In order for a color measuring device to measure color with high precision, an underlay called a backing plate may be disposed on the back side of sheet opposite the side where color is measured. By disposing a backing plate, it is possible to measure color patterns with high precision, and as a result, take accurate measurements of color information. For example, it is possible to keep the color of a paper discharge guide disposed with the backing plate from showing through the sheet and making it difficult to take accurate measurements of color information for the color patterns.
The color of a backing plate is defined by ISO as a white backing or a black backing. Such backing plates may be attached or removed at an attachment position by the magnetic force of a magnet. Consequently, it is possible for the user to change and use multiple backing plates with different colors.
Japanese Patent Laid-Open No. 2008-275587 discloses a technique of using a color measuring device to measure the color of a backing plate and determine the color of the attached backing plate.
With the color measuring device described in Japanese Patent Laid-Open No. 2008-275587, a white backing plate and a black backing plate are provided separately. For this reason, the user is required to keep the backing plate not in use. Additionally, it is necessary to keep the backing plate such that the backing plate does not become warped. This is because if the backing plate warps, it may not be possible to measure color with high precision.
Particularly, backing plates used in a printing apparatus that prints large-format sheets become longer in correspondence with the width of the sheet. Consequently, it maybe difficult to keep particularly long backing plates. Also, long backing plates may become warped depending on how the backing plates are placed, particularly when kept for long periods. If a backing plate warps, the distance between a sheet disposed on the backing plate and the color measuring sensor is no longer constant, and it may not be possible to measure color with high precision.